FRANKLINTON, N.C. -- President Bush toured a laboratory working to convert wood chips to ethanol Thursday, touting his plan to boost U.S. use of the home-grown fuel fivefold over 10 years.

In his State of the Union speech in January, Bush floated a plan to raise U.S. biofuels production five times current levels by 2017 to help reduce reliance on Middle East oil.

Bush's plan bets heavily on advances in making ethanol from cellulosic sources like wood chips and switchgrass rather than from corn -- the dominant feedstock in most current U.S. ethanol supplies.

"I wouldn't have done that if I didn't think it were achievable," Bush said after he toured a Franklinton, North Carolina, lab owned by Novozymes North America Inc., which researches the use of enzymes to produce cellulosic ethanol.

Bush's plan has drawn skepticism from big U.S. oil companies such as Exxon Mobil Corp., and some analysts have referred to cellulosic ethanol as the "Holy Grail" of fuel sources, because it relies on so far unproven science.

The U.S. government's own top energy forecaster is not betting that Bush's plans for 35 billion gallons a year of renewable fuels by 2017 will succeed.

The U.S. Energy Information Administration, the Energy Department's statistical arm, sees U.S. ethanol production reaching just 11.5 billion gallons a year in 2017.

White House spokesman Scott Stanzel said that the EIA has in the past been "conservative in its forecasts."

Stanzel said Bush "is putting faith in the power of American ingenuity to develop the technologies that are going to create the advancements needed to meet his ambitious goal."

The White House says that up to 15 billion gallons per year of ethanol could come from corn-based sources alone by 2017.

Bush said his plan might look like a "pipe dream," but added, "We've got a lot of brainpower working on it."

Touring the Novozymes lab, Bush picked up a beaker filled with brownish green yeast, took a whiff and made a sour face. "I quit drinking in '86," he quipped.

Holding up a jar of clear ethanol, he said: "Someday you'll be using this in your cars."

And then picking up a jar of wood chips, Bush, clad in a lab coat and protective goggles, said: "It's hard to believe this can be converted into energy. But it's going to happen."

The government has set aside $375 million to fund bioenergy research centers to reach the goal.